A Survey for Fast Transients in the Fornax Cluster of Galaxies

The luminosity gap between novae (MR ≤ −10) and supernovae (MR ≥ −17) is well known since the pioneering research of Zwicky and Hubble. Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae. Here, we present the results of a B-band survey of 23 member galaxies of the Fornax cluster, performed at the Las Campanas 2.5-m Irene duPont telescope. Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of MB = −9.3 mag. We provide a detailed assessment of the transient detection efficiency and the resulting upper limits on the event rate as function of peak magnitude. Further, we discuss the discoveries of five previously unknown foreground variables which we identified as two flare stars, two W Uma type eclipsing binaries and a candidate δ Scuti/SX Phe star. Subject headings: surveys — stars: flare — (stars: variables:) delta Scuti — stars: variables: other